I took the 360 for it's trial run. I really like it. It pulled a little sort of like when you are using a floor machine and don't have enough liquid on the floor. I was very happy, but I'm still trying to get to a point where the traffic pattern isn't such a problem. Overall the carpet was clean but I would still like to get those traffic patterns cleaner. It's hard to tell if its dirt or we've reached a point where the finish is worn off the carpet.
Some low-face-weight tufted carpets, particularly the frieze that's so popular in this area, can "blossom out" very quickly. The tops of the tufts frizz out from even simple vacuuming if the customer has an aggressive beater bar.
This makes the area look darker because it's reflecting light back to the eye in a scattered and disorganized way.
A simple way to tell is to "grin" the fibers (part them and look at the backing) - if there's no visible soil on the backing, and a damp white towel shows no soil after patting or blotting the carpet, then likely what you're seeing in those traffic areas is
damage, not
dirt.
The 360i is a fantastic tool, but be wary of doing damage with those brush heads. You can blossom a tufted carpet in no time at all if you let it run too dry or for too long in one place.